Avalanches around Crested Butte Area

Location: Crested Butte Area
Date of Observation: 11/29/2016
Name: Zach Guy
Subject: Avalanches around Crested Butte Area
Aspect: North East, South East
Elevation: Above treelin

Avalanches: See photos. 2 large natural slab avalanches that ran sometime during the storm on NE aspects above treeline, Mt. Emmons and Mt. Axtell, both failing at the ground in old snow layers. Both showed impressive propagation considering relatively thin slabs. 2 slab avalanches that occurred mid-day on SE aspect ATL of Red Lady, apparently remotely triggered by a skier. These presumably failed on a crust or crust facet layer from that formed last week, either at the storm interface or just below it.
Weather: Clearing skies allowed views of peaks near town.
Snowpack: No avalanche activity observed on any of the N/BTL paths near town, but they now appear to have a smooth and continuous snow cover for future weak layer/bedsurfaces

Mt. Axtell. NE Aspect ATL.  SS-N-R2-D2-O/G
Mt. Emmons.  NE Aspect ATL  N-SS-R1-D1.5-O/G
Mt. Emmons, SE Aspect ATL.  SS-ASr/y-R1-D2-U

Pittsburgh Obs

Location: Paradise Divide Area
Date of Observation: 11/28/2016
Name: Alex Banas
Subject: Pittsburgh Obs
Aspect: South, South West, West
Elevation: 9,500′-10,500′

Avalanches:
Weather: Overcast skies Snowing S1 throughout the day with moderate to strong wind gusts out of the W, NW.
Snowpack: West, Southwest aspect near near treeline in the paradise divide showed decent coverage with the HS varying from 50-90cm. Storm totals overnight looked to be 20-25cm. The new snow was bonding well within the storm snow. Tests show failures on facets below a thin melt freeze crust. Steady winds throughout the day stiffened the new slab from F to 4F- 75cm down to the crust.

9,600′ SW 34* slope
HS; 90. CT 13 SC ECTP 9 SC
Both tests failed 75cm down, below a melt freeze crust. Test slope collapsed while exiting.

Anthracites/Irwin Tenure

Location: Kebler Pass Area
Date of Observation: 11/28/2016
Name: Ian Havlick
Subject: Anthracites/Irwin Tenure
Aspect: North, North East, East, South East, South, South West, West
Elevation: 10,000-11200

Avalanches: did not travel ATL, or on slopes steeper than 33º today, saw no avalanches, cracking, or collapsing.
Weather: Mid morning broken skies with spotty sun gave way to afternoon pulse with moderate snow showers becoming heavier and steadier throughout afternoon to sunset. Light to moderate west to north winds, especially on exposed ridgelines near treeline. Temperatures remained cold, with high of 16.
Snowpack: 21″ storm snow as of sunset, with 1.7″ SWE. Snow fell right-side up, lighter density snow falling on top as temps continued to plummet into late afternoon when we finished tour. Winds were actively transporting snow into 3-5 foot drifts. Nearer to treeline, wind was stiffening upper 10-12″ snow into a noticeably stiffer slab. Lots of terrain texture, downed trees, rocks, etc BTL…didnt seem like much avalanche concern in this type of terrain yet…

Dug several pits. On a 33º WSW facing slope, around 10,800ft, the nov. 21 facets were apparent and reactive with repeatable ECT failing on isolation.

On north facing, BTL, 25º slope in Anthracites, found 2 distinct layers of 3-4mm surface hoar 30cm from ground, ECTP17 RP. Digging on East bowl, found this surface hoar again–could be an issue with stiffening/settling slab in future?

IMG_0096
Screen-Shot-2016-11-28-at-6.03.17-PM
Screen-Shot-2016-11-28-at-6.08.50-PM

Gothic 7 a.m. report

Location: Crested Butte Area
Date of Observation: 11/28/2016
Name: billy barr
Subject: Gothic 7 a.m. report
Aspect:
Elevation:
Weather: Totals for the past 24 hours are 15″ of snow with 0.96″ water of which 9″ and 0.59″ came sunset to sunrise today.

Snowing steady and moderate right now with snowpack at 18½”. Temp. is 14F. No visibility but no sound of any slide activity and down low here it is still safe. Higher up starting to get a little shaky (he says sitting in the warmth of his house and not going anywhere near there). Wind 0-3 W. billy

Near Treeline Obs

Location: Paradise Divide Area
Date of Observation: 11/27/2016
Name: Evan Ross
Subject: Near Treeline Obs
Aspect: North East, East, South East
Elevation: 11,000

Avalanches: Remote triggered one persistent slab from a couple hundred feet away. Shooting cracks spanning multiple aspects of a gully that pulled out a small avalanche on a steeper 40ish degree slope.
Weather: Snowfall rates in the S1-S5 range throughout the day. Gusty down valley winds blowing, swirling and drifting new snow about. Never made it to ridegline.
Snowpack: HS about 50-60 cm on East and Southeast Aspects. Generally fist hard snow consisting of the Thanksgiving and the current storm without an obvious or reactive interface between them. These storms where resting on a varying thickness and generally soft crust just above the ground. No signs of instability on the slopes traveled. This would have likely been a different story on slopes with additional wind loading.

HS about 65-70cm on Northeast aspects. The Thanksgiving storm had more slab structure 4f- and was sitting over about 10-15cm of 2mm faceted particles. Shooting cracks and collapses while traveling near these slopes. Persistent slab avalanches felt likely to trigger on convex terrain features or slopes over 35 degrees. Small NSF also looked to be present at the interface of the Thanksgiving and todays storm, though didn’t get much time to look into it more.

Below treeline slopes generally lacked enough snow for an avalanche problem, except for potentially a very isolated and wind effected terrain feature.

65cm crown of a small remotely triggered persistent slab.

IMG_2329

Flank profile dug into some shooting cracks.

IMG_2323

Shooting cracks ran down the middle (northeastern) and right (norther) slopes of this gully.

IMG_2324

Gothic 7 a.m. report

Location: Crested Butte Area
Date of Observation: 11/27/2016
Name: billy bar
Subject: Gothic 7 a.m. report
Aspect:
Elevation:

Avalanches:
Weather: Strong wind from 5:30 to 6:15 but now light again. Snow at sweep time 3″ new and 0.23″ of water. Temp. holding at 24F and clouds have lifted some. Snow paused the past half hour but just starting up again very light. Snow depth at winters deepest of 9″. billy
Snowpack:

Anthracite area

Location: Kebler Pass Area
Date of Observation: 11/26/2016
Name: Alex Banas
Subject: Anthracite area
Aspect: North, North East
Elevation: 10-11,200′
Weather: Clear skies, calm wind from the west. Temps in the mid 20’s.
Snowpack: Overall weak and shallow snowpack observed throughout Anthracite Zone. The persistent slab problem was not observed below treeline. At treeline the persistent slab problem produced numerous collapses and visible cracking throughout the test slope area. 11,200′ NE 33* Surface grains: .5-1.5mm Facets/DF HS: 53cm CT 13 SC ECTP 9 SC Both failed 37cm down in 2-6mm depth hoar.

HS showed a shallow snowpack from 15-53cm. Surface hoar was observed on shady slopes below treeline while none was observed near treeline in open wind affected areas.

10,325′ North East
HS: 20cm Surface hoar observed wide spread on shady slopes.

10,900′ N 30* slope
HS: 35cm. Depth hoar capped by a 1cm melt freeze crust. Facets to the surface.

11,200′ NE 33* Persistent slab structure found
HS: 53cm CT 13 SC ECTP 9 SC Both failed 37cm down in large facets

IMG_1663-1
FullSizeRender

South aspect

Location: Paradise Divide Area
Date of Observation: 11/24/2016
Name: EM
Subject: South aspect
Aspect: South East, South, South West
Elevation: 10000 – 12500

Avalanches: several small windslabs were visible throughout the range. All were confined to Wednesday nights snowfall.
Weather: Clear skies with cold valley temps and strong winds transporting snow off many alpine features and peaks in AM. Around noon winds had eased off and snow transport mostly stopped.
Snowpack: Many low elevation areas closer to 10k were composed of snowfall from just this past week. With snow from earlier storms melting off. Closer to treeline there was generally a suncrust at the ground covered by the previous weeks snowfall. Some slopes above 115000 had cohesive slab developed above this crust from past weeks snow and wind. Several locations showed this interface to be bonded relatively well.
At one location, 12500, south facing, 29*, start zone just below ridge top, we found that the wind blown snow from Wednesday night had bonded poorly to the snowfall from earlier in the week. Easy to moderate, Q2 results 18 cm down on surface facets (seemed slighly to thick of layer to be surface hoar). This location had clearly been stiffened by winds that came with the previous nights snowfall. We actively avoided this area of slabby snow. More protected features down slope didnt have this surface slab structure.

Purple Ridge

Location: Paradise Divide Area
Date of Observation: 11/24/2016
Name: Chris Miller
Subject: Purple Ridge
Aspect:
Elevation:

Avalanches: See photos
Weather:
Snowpack: Collapse and shooting cracks on N/NE purple ridge

Small windslab pockets on Richmond
Small windslab on Purple Ridge
Shooting cracks
North Cirque on Augusta

Gothic Obs

Location: Crested Butte Area
Date of Observation: 11/24/2016
Name: billy barr
Subject: Gothic Obs
Aspect:
Elevation:
Snowpack: Turning cloudy after dark with strong wind and light snow starting around 9:30 p.m. and going all night, though seemingly letting up near sunrise. Only 2″ new snow and 0.13″ water but a lot of snow transport with the wind so drifting. Snow pack at 6″ deep, tied for the deepest so far this winter. Currently overcast with light to moderate west wind and very light snow. billy